17.1 CLIMATE AND ITS CAUSES

Learning Targets

1. Describe the effect of latitude on climate

2. Diagram the Hadley, Ferrell, and Polar atmospheric circulation cells and show how they influence the climate of various locations

3. Discuss position in the global wind belts, proximity to a large water body, position relative to a mountain range

Climate1. Climate is the long-term

average of weather2. Weather is unpredictable3. Climate is predictable

Climate1. Factors influencing region’s

climate:a) Latitudeb) Three Global Wind Beltsc) Prevailing Windsd) Continental Positione) Ocean Currentsf) Altitude

Factor # 1 - Latitude1. The main factor influencing region’s

climate2. Low latitude = high solar energy

a) Equatori. Sun directly overhead; equal night and

day3. High latitude = low solar energy

a) Polesi. Sun at low angle; long days, long nightsii. High albedo

Factor # 2 – Global Wind Belts #1

1. ITCZ – Intertropical Convergence Zone

a)Low Pressure boundary between two Hadley Cells, lots of precipitation.

b)Equator 00 - Doldrums

Factor # 2 – Global Wind Belt #2

1.Hadley and Ferrell Cell Boundarya)High Pressure – sinking cold air

causing evaporationb)Horse latitudes - 300 N/S

Factor # 2 – Global Wind Belt #3

1.Ferrell and Polar Cell Boundarya)Polar jet stream – cold air from

poles meet warmer air from tropics, very stormy

b)500 to 600 N/S latitude

Factor # 3 - Prevailing Winds1. Global wind belts create H and L

zones2. Bring weather from locations

they come from3. H Dry

a) Cold air descending causes evaporation

4. L Weta) Warm air rising and losing its

water

Factor # 4 - Continental Position1. Water regulates air temperature

a) Higher specific heat than land2. Maritime climate – influenced

by nearby large body of watera) Less extreme

3. Continental climate – greater temperature differences between day/night & summer/winter

a) More extreme

Factor # 5 - Ocean Currents1. Surface and deep water currents

affect air temperatures along the coast

2. Cold water moves towards the equator

a) California current cools Southern California

3. Warm water moves towards the poles

a) Gulf stream warms Northern Europe

4. Cold upwelling can cool or heat surrounding land

Factor # 6 - Altitude1. Mountains affect climate by

a) Lowering temperaturei. Temperature decreases with

altitude in the troposphereb) Rainshadow Effect

i. Air is dry after it has been forced over mountains no precipitation

ii. e.g. California compared to Nevada